Rosacea is a common chronic skin disease that is often manifested as redness on the face, specifically the cheeks, nose, chin and forehead, as well as the appearance of small bumps called papules and pustules and highly visible blood vessels. It afflicts between 5 to 20 percent of the population worldwide and around 16 million people in the United States alone. At present, the exact cause behind rosacea is still unclear and there is presently no complete cure available for it.

However, a new study conducted by Kevin Kavanagh of the National University of Ireland revealed a link between rosacea and tiny mites that live in the pores of people’s face. These microscopic eight-legged mites, known as Demodex folliculorum, occur among 20 to 80 percent of adults, with healthy adults typically having one or two mites per square centimetre of facial skin. They feed off the oily sebum that coats the skin and thrive on the hair follicles of eyebrows and eyelashes and in the oily pores of the nose, forehead and cheeks.

However, it has been discovered that adults who suffer from rosacea can host as many as ten times the number of mites. Changes in the skin brought about by aging, stress, illness and damage due to heat and humidity can increase the amount of sebum and change its composition, thereby helping the mites thrive.

Since the mites have no anus and cannot get rid of their feces, their abdomen just keeps getting bigger. When they die and decompose, the mites release all their feces into the pores. A bacteria that accumulate in the feces, Bacillus oleronius, is then released and triggers an immune reaction in the skin that leads to inflammation and tissue damage. The greater the number of mites, the worse the rosacea flare-up is.

Kavanagh also reported in an earlier study that 80 percent of people with the most common kind of rosacea have immune cells in their blood that react strongly to two proteins from B. Oleronius, releasing triggers of inflammation. On the other hand, only 40 percent of people without rosacea have this reaction.

Some antibacterial drugs such as tetracyclines can improve rosacea by eliminating B. Oleronius. However, these antibacterial drugs do not affect the mites themselves. Thus, the study shows that one possible alternative in treating rosacea is to focus on reducing the number of mites that live on the face in order to minimize the amount of bacteria that is released onto the skin.